Code Challenges

Get better at coding with practice problems.

Coding Challenges

Select a problem, write code, run test cases, and submit your solution.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Guru

Implement the `criticalConnectionsBridgeCount` method that counts bridge edges in an undirected network.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `minimumReorderRoutesToCapital` method that returns the minimum road directions to reverse so every city can reach city zero.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `alienDictionaryOrderSize` method that returns the size of a valid alien character order.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `eventualSafeNodesCount` method that counts nodes that cannot reach a cycle.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `networkDelayTimeCost` method that returns the time needed for a signal to reach all nodes.

Tree Binary Tree Binary Search Tree Breadth First Search Depth First Search

Intermediate

Implement the `sumRootToLeafNumbers` method that returns the sum of all root-to-leaf numbers in a binary tree.

Tree Binary Tree Binary Search Tree Breadth First Search Depth First Search

Intermediate

Implement the `countGoodNodesBinaryTree` method that counts good nodes in a binary tree.

Tree Binary Tree Binary Search Tree Breadth First Search Depth First Search

Intermediate

Implement the `symmetricBinaryTreeCheck` method that checks whether a binary tree is a mirror of itself.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `minimumEffortPathGrid` method that returns the minimum effort required to travel across a height grid.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `countProvincesUnionFind` method that counts connected city groups from an adjacency matrix.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `findRedundantConnection` method that returns the edge that creates a cycle in an undirected graph.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `cheapestFlightWithinKStops` method that finds the cheapest price from source to destination within a stop limit.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Learner

Implement the `floodFillChangedCount` method that returns how many cells are changed during flood fill.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Proficient

Implement the `dijkstraShortestPathSimple` method that returns the shortest weighted path using Dijkstra-style logic.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `minimumSpanningTreeWeightSimple` method that returns the total weight of a minimum spanning tree.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `bipartiteGraphCheck` method that checks whether a graph can be divided into two valid groups.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `connectedComponentsCount` method that counts connected components in an undirected graph.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `shortestPathUnweightedGraph` method that returns the shortest distance between two nodes in an unweighted graph.

Graph Breadth First Search Depth First Search Shortest Path Minimum Spanning Tree

Intermediate

Implement the `detectCycleDirectedGraph` method that checks whether a directed graph contains a cycle.